Question

Syringes are used to take blood for blood samples. The pressure of the blood forces the liquid to move into the syringe when the plunger is withdrawn.

• A. True
• B. False

Answer 1

The correct option is A

True

The syringe works due to application of atmospheric pressure. It has the same working principle as that of a siphon (shown below). In a siphon, the pressure inside the bottle decreases when the bottle is pressed and released. Thus causes the flow of the liquid from a high-pressure region to this low-pressure region.

The pressure inside the syringe is low and the body is at atmospheric pressure. Therefore, there is a pressure difference. As the plunger is withdrawn, the high pressure blood inside the body pushes to this low-pressure syringe. So, the given statement is true.